July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Light adaptation of the photopic electroretinogram in healthy subjects, and in patients with diseases affecting ganglion cells, the retinal pigment epithelium and the rod system
Author Affiliations & Notes
  • ZIHE XU
    Ophthalmology, King’s College London, St Thomas’ Hospital Campus, LONDON, United Kingdom
  • Xiaofan Jiang
    Ophthalmology, King’s College London, St Thomas’ Hospital Campus, LONDON, United Kingdom
  • Isabelle Chow
    Ophthalmology, King’s College London, St Thomas’ Hospital Campus, LONDON, United Kingdom
  • Mathura Indusegaran
    Ophthalmology, King’s College London, St Thomas’ Hospital Campus, LONDON, United Kingdom
  • Zainab Saleem
    Ophthalmology, King’s College London, St Thomas’ Hospital Campus, LONDON, United Kingdom
  • Gordon T Plant
    Ophthalmology, King’s College London, St Thomas’ Hospital Campus, LONDON, United Kingdom
    Neuro-ophthalmology Service, Moorfields Eye Hospital, LONDON, United Kingdom
  • Andrew Webster
    UCL Institute of Ophthalmology, LONDON, United Kingdom
    Retinal Service, Moorfields Eye Hospital, LONDON, United Kingdom
  • Christopher J Hammond
    Ophthalmology, King’s College London, St Thomas’ Hospital Campus, LONDON, United Kingdom
    The Department of Twin Research & Genetic Epidemiology, King’s College London St Thomas’ Campus, London, United Kingdom
  • Omar Abdul Rahman Mahroo
    Ophthalmology, King’s College London, St Thomas’ Hospital Campus, LONDON, United Kingdom
  • Footnotes
    Commercial Relationships   ZIHE XU, None; Xiaofan Jiang, None; Isabelle Chow, None; Mathura Indusegaran, None; Zainab Saleem, None; Gordon Plant, None; Andrew Webster, None; Christopher Hammond, None; Omar Mahroo, None
  • Footnotes
    Support  Wellcome Trust Grant 206619/Z/17/Z; NIHR Biomedical Research Centre at Moorfields Eye Hospital and the UCL Institute of Ophthalmology; Fight for Sight UK
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 2501. doi:
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      ZIHE XU, Xiaofan Jiang, Isabelle Chow, Mathura Indusegaran, Zainab Saleem, Gordon T Plant, Andrew Webster, Christopher J Hammond, Omar Abdul Rahman Mahroo; Light adaptation of the photopic electroretinogram in healthy subjects, and in patients with diseases affecting ganglion cells, the retinal pigment epithelium and the rod system. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2501.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : After a period of dark adaptation, the electroretinogram (ERG) response to flashes delivered in the presence of a photopic background increases in amplitude over several minutes. This has been termed the Light Adaptation Effect (LAE). The underlying processes are not known. A rise in potential occurs over the retinal pigment epithelium (RPE) over a similar time course, and, in animal models, intrinsically photosensitive ganglion cells have been implicated in ERG light adaptation. Also, rod system activity is thought to influence cone system signal transmission. We explored the LAE using international standard photopic flash and background stimuli in 8 healthy subjects and 3 patients with specific retinal diseases.

Methods : In each experiment, the subject dark adapted for 20 minutes and was then exposed to a standard white background (30 cd m-2). White flashes (3 cd m-2 s) were delivered (in groups of 36 flashes, repeated every 2 minutes) for the next 20 minutes. Pupils were pharmacologically dilated and responses recorded using conductive fibre electrodes. The patients (a 23 year old with Best disease, with an absent RPE light rise; a 54 year old with unilateral loss of retinal ganglion cells; a 69 year old with unilateral loss of rod-driven inner retinal signaling) were recruited from ophthalmology clinics, having been diagnosed based on prior examinations including imaging and electrophysiology.

Results : In the 8 healthy subjects (mean age, 26.6 years; range, 21-39 years), the b-wave amplitude approximately doubled over the recording period. The amplitude rose with time, reaching a relative plateau at 10 min, with minimal or very slow increase in amplitude thereafter. The time-course was similar in the eyes of the affected patients. In addition, in the two patients with unilateral disease, the LAE kinetics in the affected eye were similar to the control eye.

Conclusions : The findings support the standard recommendation of 10 min light adaptation prior to photopic recordings, as by this time a relative steady state is reached. The processes underlying the LAE do not depend on the light rise over the retinal pigment epithelium, nor on the presence of the retinal ganglion cell population, and appear to occur in the absence of rod-driven inner retinal signals.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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